Procedure-dependence and Tissue Factor-independence of Hypercoagulability during Orthopaedic Surgery

Early myocardial injury and coagulation activation in thoracoscopic left atrial appendage clipping

BACKGROUND

Thoracoscopic left atrial appendage clipping as a new strategy for stroke prevention. This study was established to observe the changes in myocardial injury and coagulation during the perioperative to provide the basis for anticoagulation strategy.

METHODS

Fifty-two patients with nonvalvular atrial fibrillation who completed thoracoscopic left atrial appendage clipping alone and 52 matched controls with thoracoscopic lobectomy were included in the study. The changes in coagulation and myocardial enzyme during the perioperative period were compared by t-test or nonparametric test. Linear correlation analysis was performed on the trend changes of each indicator in the left atrial appendage clipping group.

RESULTS

Compared with the control group, the postoperative cardiac troponin I level in the thoracoscopic left atrial appendage clip group was significantly higher than that before the operation; there was no significant difference in the increase of myoglobin between the two groups. In the coagulation function, there was no significant difference in the increase of fibrinogen between the two groups. Postoperative D-dimer and fibrin degradation products were significantly increased, especially the left atrial appendage clip group was significantly higher than the control group, and even showed a trend of secondary increase. Cardiac troponin I was positively correlated with C-reactive protein, fibrinogen and von Willebrand Factor activity, and the Spearman nonparametric correlation coefficients were 1, 0.829, and 0.829, respectively (all p < .05).

CONCLUSION

Thoracoscopic left atrial appendage closure surgery presents early myocardial injury and activation of coagulation function. The secondary increase of coagulation index needs our attention.

Tissue factor pathway inhibitor 2 as a serum marker for diagnosing asymptomatic venous thromboembolism in patients with epithelial ovarian cancer and positive D-dimer results

Tissue factor pathway inhibitor 2 (TFPI2) is a serodiagnostic marker for epithelial ovarian cancer (EOC) and is the primary inhibitor of the extrinsic coagulation pathway. The present study assessed the diagnostic performance of TFPI2 for detecting venous thromboembolism (VTE) in patients with EOC and positive D-dimer results (>1.0 µg/ml). First, the clinical data of 81 patients with EOC admitted to Nara Medical University Hospital between January 2008 and December 2015 were collected. Also, 25 patients with VTE and 56 patients without VTE were included. Receiver-operating characteristic (ROC) curve analyses were performed to determine the diagnostic efficacy of TFPI2 in discriminating patients with VTE from those without VTE. Serum TFPI2 levels in patients with VTE were significantly higher than in non-VTE patients (median, 472.2 vs. 279.1 pg/ml, P<0.001). Using the Youden index, the optimal cutoff value for the TFPI2 level was set at 398.9 pg/ml. Furthermore, the sensitivity, specificity, positive predictive value and negative predictive value of TFPI2 for diagnosing VTE were 64.0, 80.4, 59.3 and 83.3%, respectively. Additionally, 80.4% of patients with TFPI2 levels <398.9 pg/ml were VTE-negative. ROC analysis demonstrated that the area under the curve for TFPI2 was 0.729 (95% confidence interval, 0.614-0.844). Conclusively, TFPI2 may distinguish patients with VTE from those without VTE among patients with EOC and positive D-dimer results.

Is Apixaban Safe and Effective for Venous Thromboembolism Prophylaxis After Primary Total Hip and Total Knee Arthroplasties?

BACKGROUND

Venous thromboembolism (VTE) is a serious complication of total hip arthroplasty (THA) and total knee arthroplasty (TKA). Apixaban is approved for VTE prophylaxis. This study seeks to ascertain the risk of VTE and bleeding complications in patients undergoing primary THA and TKA receiving apixaban for postoperative VTE prophylaxis for one of the following indications: high risk for VTE, previously on apixaban, and contraindication to the use of aspirin.

METHODS

This is a retrospective cohort study of patients who underwent primary THA or TKA over a 17-month period and were prescribed apixaban for thromboprophylaxis postoperatively.

RESULTS

230 patients were included in the study, 110 TKA and 120 THA. The primary reasons for high-risk VTE status included personal and family history of VTE, and 13% were taking apixaban preoperatively for atrial fibrillation. 1 patient (0.43%) who underwent TKA had a DVT with PE. 2.6% of patients had wound complications requiring operative treatment, and 0.87% of THA patients underwent revision arthroplasty.

CONCLUSION

The use of apixaban for VTE prophylaxis after primary THA and TKA in patients at high risk for VTE, in patients previously on apixaban, and in patients with a contraindication to the use of aspirin is associated with a low risk of VTE and bleeding complications.

Tissue Factor and Tissue Factor Pathway Inhibitor in the Wound-Healing Process After Neurosurgery

Objectives:

The aim of the study was to assess the concentrations of tissue factor (TF) and tissue factor pathway inhibitor (TFPI) in the blood of patients with a postoperative wound after neurosurgery.

Method:

Participants included 20 adult patients who underwent neurosurgery because of degenerative spine changes. The concentration of TF and TFPI in the patients’ blood serum was measured 3 times: before surgery, during the first 24 hr after surgery, and between the 5th and 7th days after surgery. The control group comprised 20 healthy volunteers similar to the patient group with respect to gender and age.

Results:

A statistically significant difference was observed between TF concentration at all three measurement time points in the research group and TF concentration in the control group ( p = .018, p = .010, p = .001). A statistically significant difference was found between TFPI concentration at the second time point in the research group and TFPI concentration in the control group ( p = .041). No statistically significant within-subject difference was found between TF concentrations before and after surgery. A statistically significant within-subject difference was found between TFPI concentrations within 24 hr after surgery and 5–7 days after surgery ( p = .004).

Conclusion:

High perioperative concentrations of TF indicate not only the presence of thrombophilia but also the importance of TF in the wound-healing process. Perioperative changes in TFPI concentrations are related to its compensatory influence on hemostasis in thrombophilic conditions.

Sustained release of tissue factor following thrombosis of lower limb trauma

This study was undertaken to provide evidence for the mechanism of venous thromboembolism (VTE) in healthy patients with minor lower limb injury (fracture; Achilles tendon rupture) that was medically managed with plaster cast/brace immobilization. The Plaster Cast clinical trial provided a unique opportunity to identify the natural history of VTE using placebo-controlled patients (n = 183) with validation of the mechanism using the low-molecular-weight heparin (LMWH; reviparin)-treated patients (n = 182). Confirmed VTE in this population was associated with a burst of tissue factor release (and a minor fibrinolytic deficit) leading to thrombin generation that was sustained at least 5 weeks, greater with fractures than with soft-tissue injuries and greater with surgery than with conservative treatment. The root cause likely involves platelet/leukocyte activation (inflammation) rather than endothelial cell injury. Thromboprophylaxis with a low dose of LMWH reduced thrombin generation, with patients undergoing surgery benefitting the most.

Continuous passive motion for preventing venous thromboembolism after total knee arthroplasty

BACKGROUND

Total knee arthroplasty (TKA) is a common form of orthopaedic surgery. Venous thromboembolism (VTE), which consists of deep venous thrombosis (DVT) and pulmonary embolism (PE), is a major and potentially fatal complication after TKA. The incidence of DVT after TKA is 40% to 80% and the incidence of PE is approximately 2%. It is generally agreed that thromboprophylaxis should be used in patients who undergo TKA. Both pharmacological and mechanical methods are used in the prevention of DVT. Pharmacological methods alter the blood coagulation profile and may increase the risk of bleeding complications. When pharmacological methods cannot be used the mechanical methods become crucial for VTE prophylaxis. Continuous passive motion (CPM) is provided through an external motorised device which enables a joint to move passively throughout a preset arc of motion. Despite the theoretical effectiveness and widespread use of CPM, there are still differing views on the effectiveness of CPM as prophylaxis against thrombosis after TKA. This is an update of the review first published in 2012.

OBJECTIVES

The aim of this review was to determine the effectiveness of continuous passive motion (CPM) therapy for preventing venous thromboembolism (VTE) in patients after total knee arthroplasty (TKA).

SEARCH METHODS

For this update the Cochrane Peripheral Vascular Diseases Group Trials Search Co-ordinator searched the Specialised Register (last searched February 2014), CENTRAL (2014, Issue 1), Ovid MEDLINE (to week 1 February 2014) and EMBASE (to Week 07 2014).

SELECTION CRITERIA

Randomised controlled trials (RCTs) comparing the use of CPM with control in preventing DVT or PE after TKA. People aged 18 years and older who had undergone TKA were included in this review. We excluded studies of patients who presented with DVT at baseline. The experimental and control groups received similar postoperative care and therapy other than the CPM.

DATA COLLECTION AND ANALYSIS

Two review authors independently assessed the citations retrieved by the search strategies for reports of relevant RCTs. They independently selected trials that satisfied the inclusion criteria, extracted data and undertook quality assessment. Effects were estimated as risk ratios (RRs), mean differences or standardised mean differences with 95% confidence intervals (CIs). Meta-analyses were performed using a fixed-effect model for continuous variables. Where heterogeneity existed (determined by the I(2) statistic) a random-effects model was used.

MAIN RESULTS

Eleven RCTs involving 808 participants met the inclusion criteria. The methodological quality of the included studies was variable and most of the predefined outcomes were reported by only one or two studies, therefore the quality of the evidence was low. Five studies with a total of 405 patients reported the incidence of DVT. In the CPM group (205 patients) 36 developed DVT (18%) compared to 29 (15%) in the control group (200 patients). The results of the meta-analysis showed no evidence that CPM had any effect on preventing VTE after TKA (RR 1.22, 95% CI 0.84 to 1.79). One trial (150 participants) did not find PE in any of the patients during hospitalisation or in the subsequent three months. PE was not reported in the other included studies. None of the trials reported deaths among the included participants.

AUTHORS' CONCLUSIONS

There is not enough evidence from the available RCTs to conclude that CPM reduces VTE after TKA. We cannot assess the effect of CPM on mortality because no such events occurred amongst the participants of these trials. The quality of the evidence was low. The results are supported by only a small number of studies, most of which are of low to moderate quality.

Absence of tissue factor expression by neoplastic plasma cells in multiple myeloma

Thrombosis portends a poor prognosis in individuals with solid tumors. Constitutive expression of tissue factor (TF) by cancer cells is a key in triggering activation of coagulation and promoting aggressive tumor behavior. Though multiple myeloma (MM) is associated with a high frequency of thrombosis in the context of thalidomide and lenalidomide therapy, prognosis is not affected by its occurrence. We sought to determine the expression of TF in MM. F3 (TF gene) expression profiling was analyzed in 55 human MM cell lines (HMCL) and in 223 solid tumor cell lines obtained from GlaxoSmithKline (GSK) Cancer Cell Line Genomic Profiling Dataset. TF was not expressed in any of the 55 HMCLs studied, in sharp contrast to solid tumors, 90% of which showed TF expression. F3 expression was also absent in tumor samples from 239 MM patients. Immunohistochemistry for TF was negative, with either no or focal (1+) staining in 70/73 MM patients. Only three marrow biopsies were moderately (2+) positive either focally or diffusely, suggesting that in rare cases bone marrow microenvironment may support TF expression. General lack of TF expression by neoplastic plasma cells may explain why thrombosis is not predictive of poor outcome, and why aspirin prophylaxis is often effective in MM.

Continuous passive motion for preventing venous thromboembolism after total knee arthroplasty

BACKGROUND

Total knee arthroplasty (TKA) is a common form of orthopedic surgery. Venous thromboembolism (VTE), which consists of deep venous thrombosis (DVT) and pulmonary embolism (PE), is a major and potentially fatal complication after TKA. The incidence of DVT after TKA is 40% to 80% and the incidence of PE is approximately 2%. It is generally agreed that thromboprophylaxis should be used in patients who undergo TKA. Both pharmacological and mechanical methods are used in the prevention of DVT. Pharmacological methods alter the blood coagulation profile and may increase the risk of bleeding complications. When pharmacological methods cannot be used, the mechanical methods become crucial for VTE prophylaxis. Continuous passive motion (CPM) is through an external motorised device which enables a joint to move passively throughout a preset arc of motion. Despite the theoretical effectiveness and widespread use of CPM, there are still differing views on the effectiveness of CPM as prophylaxis against thrombosis after TKA.

OBJECTIVES

The aim of this review is to determine the effectiveness of continuous passive motion therapy for preventing thrombosis in patients after total knee arthroplasty (TKA).

SEARCH METHODS

The Cochrane Peripheral Vascular Diseases Group searched their Specialised Register (last searched January 2011), CENTRAL (2011, Issue 1), MEDLINE (1948 to Week 2 January 2011) and EMBASE (1980 to Week 3 January 2011). In addition, the authors searched the reference lists of identified trials.

SELECTION CRITERIA

Randomised controlled trials (RCTs) comparing the use of CPM with control in preventing DVT or PE after TKA. People aged 18 years and older who have undergone TKA were included in this review. We excluded studies of patients who presented with DVT at baseline. Both the experimental and control groups received similar postoperative care and therapy other than the CPM.

DATA COLLECTION AND ANALYSIS

Two review authors independently assessed the citations retrieved by the search strategies for reports of relevant RCTs. They independently selected trials that satisfied the inclusion criteria, extracted data and undertook quality assessment. Effects were estimated as risk ratios (RRs) or mean differences or standardised mean differences with 95% confidence intervals (CI). Meta-analyses were performed using a fixed-effect model for continuous variables. Where heterogeneity existed (determined by the I(2) statistic), a random-effects model was used.

MAIN RESULTS

Ten randomised controlled trials involving 764 participants met the inclusion criteria. Four studies with a total of 361 patients reported the incidence of DVT. In the CPM group (182 patients) 36 developed DVT (20%) compared to 28 (16%) the control group of 179 patients. The meta-analysis result showed no evidence that CPM had any effect on preventing VTE after TKA (RR 1.27, 95% CI 0.87 to 1.86). One trial (150 participants) did not find PE in any of the patients during hospitalisation or in the subsequent three months. None of the trials reported any deaths of the included participants.

AUTHORS' CONCLUSIONS

There is not enough evidence from the available RCTs to conclude that CPM reduces VTE after TKA. We cannot assess the effect of CPM on death because no such events occurred amongst the participants of these trials.

Are current thrombo-embolic prophylaxis guidelines applicable to unicompartmental knee replacement?

Symptomatic and asymptomatic deep-vein thrombosis (DVT) is a common complication of knee replacement, with an incidence of up to 85% in the absence of prophylaxis. National guidelines for thromboprophylaxis in knee replacement are derived from total knee replacement (TKR) data. No guidelines exist specific to unicompartmental knee replacement (UKR). We investigated whether the type of knee arthroplasty (TKR or UKR) was related to the incidence of DVT and discuss the applicability of existing national guidelines for prophylaxis following UKR.

Data were collected prospectively on 3449 knee replacements, including procedure type, tourniquet time, surgeon, patient age, use of drains and gender. These variables were related to the incidence of symptomatic DVT.

The overall DVT rate was 1.6%. The only variable that had an association with DVT was operation type, with TKR having a higher incidence than UKR (2.2% versus 0.3%, p < 0.001). These data show that the incidence of DVT after UKR is both clinically and statistically significantly lower than that after TKR.

TKR and UKR patients have different risk profiles for symptomatic DVT. The risk-benefit ratio for TKR that has been used to produce national guidelines may not be applicable to UKR. Further research is required to establish the most appropriate form of prophylaxis for UKR.

Markers of thrombin generation during resurfacing and noncemented total hip arthroplasty: a pilot study

BACKGROUND

Hip resurfacing arthroplasty (HRA) could be associated with an increased risk of deep vein thrombosis (DVT) compared to traditional noncemented THA because it involves greater dissection, increased kinking and distortion of the femoral vessels, takes longer to perform, and involves insertion of some cement into the femur.

QUESTIONS/PURPOSES

Does HRA lead to greater risk of thromboembolism compared with noncemented THA?

METHODS

We prospectively studied 20 patients receiving HRA and 20 receiving THA. All patients were younger than 67 years old and were similar in height, weight, American Society of Anesthesiologists status, and gender mix. Patients undergoing HRA were younger (mean, 50 versus 59 years), their surgery was longer (mean, 87 versus 65 minutes), and they required more crystalloid during surgery (mean, 2160 versus 1662 mL). Radial artery blood samples were taken at six events during surgery and assayed for prothrombin fragment F1 + 2 and thrombin-antithrombin III complex (TAT) using enzyme-linked immunosorbent assays.

RESULTS

We observed no differences in the intraoperative increases in F1 + 2 and TAT between the two groups and no differences in surgical events.

CONCLUSION

Based on these data, HRA and THA should have similar risk of thromboembolism as THA based on the parameters we measured.

LEVEL OF EVIDENCE

Level I, diagnostic study. See Guidelines for Authors for a complete description of levels of evidence.

The perioperative von Willebrand factor activity and factor VIII levels among alcohol use disorder patients undergoing total knee or hip replacement

Alcohol use disorder patients have a five-fold higher risk of postoperative bleeding complications. We measured the perioperative von Willebrand factor and factor VIII levels in consecutive patients with alcohol use disorder. In one university hospital, 105 patients scheduled for arthroplasty were screened, and 25 fulfilled inclusion criteria. Postoperatively, we found significantly decreased von Willebrand factor ristocetin cofactor values over time among alcohol use disorder patients and significantly different time courses of factor VIII levels between patients with and without a diagnosed alcohol use disorder. Blood loss was significantly increased among alcohol use disorder patients on their first postoperative day.

Association between early postoperative coagulation activation and peri-operative myocardial ischaemia in patients undergoing vascular surgery

We investigated the association of peri-operative myocardial ischaemia with activation of coagulation and endogenous fibrinolysis in patients undergoing vascular surgery. In 50 patients, continuous Holter monitoring was performed to assess peri-operative myocardial ischaemia and 12-lead electrocardiography was recorded preoperatively and 72 h postoperatively to assess myocardial infarction. Serial blood samples were drawn peri-operatively to determine the concentrations of fibrin monomers (for activation of coagulation), D-dimer (for endogenous fibrinolysis) and cardiac troponin T and I. Patients with myocardial ischaemia showed higher concentrations of fibrin monomers at 48 h, and higher concentrations of d-dimer preoperatively and at 24 and 48 h postoperatively. In patients with peri-operative myocardial ischaemia, strong positive correlations were observed between fibrin monomer and D-dimer concentrations at 15 min and 4 h postoperatively, and cardiac troponins at 15 min and at 4, 24, 48 and 72 h postoperatively. Early postoperative activation of coagulation and fibrinolysis is associated with peri-operative myocardial cell damage among patients who are at risk for, or have a history of, coronary artery disease plus peri-operative myocardial ischaemia.

Coagulation disorders of cardiopulmonary bypass: a review

BACKGROUND

Postoperative bleeding is one of the most common complications of cardiac surgery.

DISCUSSION

Extensive surgical trauma, prolonged blood contact with the artificial surface of the cardiopulmonary bypass (CPB) circuit, high doses of heparin, and hypothermia are all possible triggers of a coagulopathy leading to excessive bleeding. Platelet activation and dysfunction also occur and are caused mainly by heparin, hypothermia, and inadequate protamine administration. Heparin and protamine administration based on heparin concentrations as opposed to fixed doses may reduce coagulopathy and postoperative blood loss.

CONCLUSIONS

A better comprehension of the multifactorial mechanisms of activation of coagulation, inflammation, and fibrinolytic pathways during CPB may enable a more effective use of the technical and pharmaceutical options which are currently available.

Activation of blood coagulation in patients undergoing postoperative blood salvage and re-infusion of unwashed whole blood after total knee arthroplasty

BACKGROUND

Perioperative blood salvage is commonly used in cardiovascular surgery and has been more recently introduced in major orthopedic surgery. Limited information is available on the influence of re-infused whole blood on the hemostatic system in orthopedic patients.

MATERIALS AND METHODS

The aim of this study was to assess whether perioperative salvage and re-infusion of unwashed whole blood is associated with an activation of blood coagulation in patients undergoing total knee replacement. Consecutive patients receiving re-infusion were included in the study (n=13). Patients undergoing total knee replacement without perioperative blood salvage and re-infusion served as controls (n=6). In patients receiving re-infusion thrombin-antithrombin complexes (TAT), plasmin-antiplasmin complexes (PAP) and fibrinogen were assayed at the following times: before surgery (baseline), immediately before re-infusion (T0), immediately (T1), 2 h (T2) and 24 h (T3) after the end of re-infusion. In control patients blood samples were drawn at the average times corresponding to each of the sampling time in the patients receiving re-infusion. The first post-surgery LMWH dose was given within 12 h after surgery.

RESULTS

TAT and PAP increased after surgery both in patients receiving re-infusion and controls. An increase of TAT and PAP was observed immediately after re-infusion with respect to baseline (TAT 513.1 +/- 259.1 microg/l vs. 5.3 +/- 4.9, p<0.0001; PAP 7408.0 +/- 1892.1 microg/l vs. 461.4 +/- 217.1, p<0.0001) and to controls (TAT 60.4 +/- 26.9 microg/l, p=0.002; PAP 2208.3 +/- 1446.4 microg/l, p<0.001). The levels of TAT and PAP in patients receiving re-infusion remained high at 2 h after re-infusion compared to those of the controls (TAT 124.1 +/- 38.3 microg/l vs. 38.08 +/- 18.9, p=0.016; PAP 5690.7 +/- 1435.5 microg/l vs. 1613.9 +/- 706.0, p<0.001) and decreased 24 h thereafter. Fibrinogen level was lower in patients receiving re-infusion compared to controls.

CONCLUSIONS

Whole blood re-infusion is associated with an activation of blood coagulation in patients undergoing total knee replacement. The clinical relevance of this activation has to be tested in prospective studies with adequate sample size.

Malaysian orthopaedic surgeons' approach to venous thromboembolic disease prophylaxis: attitudes and practice

PURPOSE

To survey Malaysian orthopaedic surgeons' attitudes to and use of venous thromboembolic disease prophylaxis.

METHODS

A total of 144 orthopaedic surgeons from various governmental and private institutions responded to a questionnaire.

RESULTS

Only slightly more than half of these surgeons considered venous thromboembolic disease as common a problem in Malaysia as in western countries. The majority of surgeons (91.0%) reported using prophylaxis selectively for patients based on various indicators such as risk grading of surgery, obesity, and malignancy etc. Bleeding tendencies were cited as the greatest fear against the use of pharmacological prophylaxis. Low-molecular-weight heparin appeared to be the most commonly used pharmacological prophylaxis, used either singly or in combination with other forms of prophylaxis. The majority of surgeons employed prophylaxis until their patients were mobile.

CONCLUSION

There should be greater awareness among surgeons in Malaysia of the need for protection against venous thromboembolic disease. Current practice needs to be reviewed and further recommendations made for existing protocols.

Venous thromboembolism and its prevention in critical care

BACKGROUND

Evidence-based guidelines for the prevention of venous thromboembolism (VTE) are available for most major surgical and medical patient groups. Such guidelines have not been established for critically ill patients.

OBJECTIVE

To perform a systematic review of the prevalence of deep vein thrombosis (DVT), the efficacy of thromboprophylaxis, and the rates of thromboprophylaxis use in critically ill patients.

METHODS

Computerized literature search for relevant studies meeting prespecified criteria.

RESULTS

The rates of objectively confirmed DVT in 4 prospective studies ranged from 13% to 31%. We identified only 3 randomized trials (1 in abstract form) of thromboprophylaxis in critical care unit patients. These studies show the efficacy of low-dose heparin and low molecular weight heparin compared with no prophylaxis; however, we found no trials comparing these 2 interventions. Eleven compliance studies reported that some form of thromboprophylaxis was used in 33% to 100% of critically ill patients, although only 1 study addressed the issue of appropriate prophylaxis use.

CONCLUSIONS

Data on the epidemiology of VTE and its prevention in critically ill patients are very limited. Further research is needed to better define patient risk factors for VTE, optimal methods of thromboprophylaxis, and strategies to improve compliance with prophylaxis recommendations. In the meantime, prevention strategies, shown to be effective in other related patient groups, and general principles of individual pharmacotherapy should guide the routine use of prophylaxis during critical illness.

The activity of tissue factor pathway inhibitor in experimental models of superantigen-induced shock and polymicrobial intra-abdominal sepsis

OBJECTIVES

To study recombinant human tissue factor pathway inhibitor (rhTFPI) in a superantigen-induced shock model and in a cecal ligation and puncture (CLP) model of peritonitis in mice.

DESIGN

Prospective, randomized, experimental study.

SETTING

An experimental animal research laboratory.

SUBJECTS

Eighty BALB/c mice for the superantigen model, and 56 BALB/c mice for the CLP model.

INTERVENTIONS

In the superantigen-induced shock model, animals received rhTFPI (350 mg/kg) subcutaneously every 12 hrs (n = 30) or saline control (n = 30) for 60 hrs after staphylococcal enterotoxin B (SEB; 10 microg iv) and a sublethal dose of E. coli 0111:B4 lipopolysaccharide (LPS; 75 microg ip). Control groups received SEB alone (n = 10) and LPS alone (n = 10). In the CLP model, rhTFPI or saline was given every 8 hrs for 48 hrs by using a 21-gauge needle (n = 9) or 23-gauge needle (n = 14) for CLP. A sham surgery control group (n = 10) was also included.

MEASUREMENTS AND MAIN RESULTS

There was 0% mortality in the SEB and LPS control groups. The mortality rate was 64% in the saline control group that received both SEB and LPS (19 of 30), whereas the rhTFPI- treated animals had a mortality rate of 20% (6 of 30; p < .01). The rhTFPI-treated group had significantly lower interleukin-6 levels (61.8 +/- 41 pg/mL vs. 285 +/- 63 pg/mL; p < .05) than the control group but no differences in tumor necrosis factor-alpha or interferon-gamma levels. In the CLP experiment, rhTFPI-treated animals did not have any survival advantage over the control group after the large-bore (21-gauge) needle puncture. The rhTFPI group had significantly improved 7-day mortality rate after CLP with the small-bore needle (23-gauge; 21.4% [rhTFPI] vs. 71.4% [control], p < .01). Plasma LPS, interleukin-6, interferon-gamma, and tumor necrosis factor-alpha levels were unchanged by rhTFPI treatment, but significantly reduced LPS (p = .006) and IFNgamma (p = .001) levels were found in the peritoneal fluid.

CONCLUSIONS

Tissue factor pathway inhibitor significantly improves the mortality rate in models of superantigen-induced shock and polymicrobial intra-abdominal infection, supporting its potential use in clinical trials for septic shock.